Process for the manufacture of solid rods and tubes made of glass or other melted material



Sept. 12, 1933. E. LE COULTRE 1,926,905

PROCESS FOR THE MANUFACTURE OF SOLID RODS AND TUBES MADE OF GLASS OR OTHER MELTED MATERIAL Filed April 20, 1931 C ,5, Cow/1 v6N TAR,

Patented Sept. 12, 1933 PROCESS FOR THE MANUFACTURE OI SOLID RODS AND, TUBES MADE OF GLASS OR OTHER LIELTED MATERIAL Ernest Le Coultre, Paris, France Application April 20, 1931, Serial No. 531,536, and in France May 22, 1930 Claims. (oi. 49-17.!)

The present invention, made by Mr. Le Coultre, has for object improvements in proceses for drawing molten materials in a hollow or solid cylindrical or like shape.

5 Experience has shown that for drawing a solid rod or a tube made of glass or of melted material ina homogeneous manner, that is to say for particularly giving to the same a uniform wall thickness, a regular diameter, a perfect cylindrical shape, it is necessary to impart to this rod or to this tube a movement of rotation on itself immediately it issues from the draw-plate. In fact, this rotation allows to obtain a uniform cooling of the walls, this causing a uniform lengthening of the entire periphery of the drawn tube which is then straight, regular and cylindrical.

Various devices have been used up to now for imparting this movement of rotation to the tube or rod; some of these devices, of a purely mechanical character, have been found very complicated to construct and very diflicultly utilizable in practice; the others, which consist in sending tangentially to the wall one or more jets of gas, air for instance, within the tube in such a manner that the friction of the gas against the wall mechanically generates the desired rotation, have proved to be of doubtful and irregular efficiency.

The present invention has for object a new process allowing to obtain the desired rotation in a positive and very simple manner. According to the invention, the rotation of the solid rod or of the tube, when issuing from the drawplate, is obtained by creating a difference of elongation between the veins or streams of the glass or of the molten material located on the opposite generatrices of the cylinder constituted by the rod or tube. According to a preferred form of execution, this difierence of elongation is obtained by arranging at the outlet of the drawplate, either outside the solid rod or tube, or within the tube, or within and outside the tube, a suitable heating device extending along a generatrix of the rod or tube, whilst the opposite generatrix remains subjected to the surrounding temperature, or to the action of a suitable cooling means.

Figs. 1 and 2 diagrammatically illustrate how the movement of rotation is obtained.

Figs. 3 and 4 illustrate, by way of a nonlimitlng example, a form of carrying out the process.

In Figs. 1 and 2, are shown at at; and cd two diametrically opposed portions of glass streams before they reach the level of the heating desame length. when, according to the present invention. a diflerence of elongation has been produced between these two streams ab has become as and cd has become of longer than ae. If the tube beingdrawn was subjected to no other force than that resulting from the diiference of elongation produced, it would tend to curve or bend towards the stream which has lengthened to the lesser degree (Fig. 1). But the weight of the tube and the pull due to the drawing machine are greater than this bending stress, and the longer stream of is compelled to move obliquely according to cg (Fig. 2); the following stream portions are subjected to a similar action, resulting in the desired rotation of the tube or rod, owing to the rotation of the stream of greatest elongation about the stream of smallest elongation.

Fig. 3 shows, by way of example, an application of the process according to the invention to a solid rod.

The liquid glass contained in the vat 1 passes through the draw-plate 2 and a suitable mandrel 3 controls the outflow of glass. Near the outlet of the draw-plate 2 is arranged a device 4 which creates a difference of temperature along two opposite, portions. of generatrices of the rod 5: burners for example or, inversely, jets of air under pressure.

One of the generatrices lengthens thus to a greater extent than the opposite generatrix, this causing the rotation of the rod 5, as explained above. The glass rod is then taken by a drawingmachine comprising a certain number of grooved pulleys 7, rotating in the same direction, above which are mounted a same number of rollers 8 turning in the opposite direction; the axis of rotation of the said rollers can advantageously be inclined relatively to the axis of rotation of the grooved pulleys, in a known manner, so as not to disturb the rotation of the rod 5 and even favorize the same.

Fig. 4 illustrates a similar device used in the case of a tube 8. As previously, a suitable heating device, for instance a burner 4, is provided. It can be replaced by a device for injecting gas at the required temperature, this gas passing within the mandrel 3, or the action of these two device can even be combined. A draw-plate asymmetrically re-heated can also be provided.

It is to be understood that the desired difference of elongation can be obtained not only by asymmetric re-heating as above, but also by an asymmetric cooling; it suflices to send, through the burner 4 or through the tube provided in the mandrel 3, gas at a suitable temperature, the cooling taking place through the exterior, through the interior, or through both sides at the same time. This cooling can also be obtained in any other manner, for instance by means of a member maintained relatively cold and arranged in the immediate vicinity of the tube or rod, and

which can even be constituted by a suitably cooled portion of the draw-plate. The diflference of elongation can also be effected by an asymmetric protection of the rod 5 or of the tube 6 against natural cooling in proximity to the draw-plate. Instead of arranging the heating or cooling device parallel to the axis of the rod or tube, this device can also be arranged according to an oblique direction, or according to a portion of a helix directed in accordance with the direction of rotation it is desired to impart to the streams of molten material.

Finally, the invention, particularly described by way of example in its application to the manufacture of a glass rod or tube, can be applied to the manufacture of a rod or tube made of any other molten material.

I claim:

1. Process for the manufacture of rods or tubes made of melted material, according to which a rotation is imparted to the material when it is being drawn, in order to obtain a truly cylindrical shape, characterized in that a difference of tem perature is produced on two corresponding portions of opposite generatrices of the rod or tube when it issues from the draw-plate, the heat or cold being produced asymmetrically on the respective generatrices.

2. Process for the manufacture of rods and cent generatrix of the rod or tube.

tubes made of melted material, by drawing the material through a draw-plate, characterized in that two corresponding portions of opposite generatrices of the rod or tube, when the same issues from the draw-plate, are subjected to different temperatures asymmetrically applied to the respective generatrices to impart a rotatable effect on the rod or tube.

3. Device for the manufacture of rods and tubes made of melted material, comprising a draw-plate, means for drawing, the molten material through this draw-plate, and heating means arranged near the said draw-plate and near the surface of the. rod or tube, said heating means operating to'apply heat asymmetrically along a single generatrix of the said rod or tube.

4. Device for the manufacture of rods and tubes made of melted material, comprising a drawplate, means for drawing the molten material through this draw-plate and cooling means arranged near the said draw-plate and near the surface of the rod or tube, along one single generatrix only of the said rod or tube, said cooling means operating to cool asymmetrically the adja- 5. Device for the manufacture of tubes made of melted material comprising a draw-plate, a hollow mandrel, arranged according to the axis of this draw-plate, means for drawing the molten material through the annular interval between the draw-plate and the mandrel, the said mandrel having at its end a gas outlet orifice adapted to laterally direct a jet of gas along one generatrix of the inner wall of the drawn tube.

ERNEST LE COULTRE. 

